Plumbing and heating pipe systems of the above-mentioned kind have been used for some time both in the construction of new housing and in renovation and repair work in old buildings, because such systems have proven satisfactory relative to the conventional metallic pipe systems mainly due to the fact that there are no corrosion problems and the pipe systems can be installed much more easily and at less expense.
Such systems comprise essential connecting elements between the plastic pipes and the fittings used as well as between the pipes themselves in the form of reducers and pipe sleeves. Also comprised are shut-off valves made of plastic material and having metallic valve seats, as well as pressure-type screw connections for hot water and aggressive liquids and also special reducers for connection to radiators. Furthermore, such a system comprises special means for assembling the above-mentioned elements with the plastic pipes, i.e. mounting devices.
Such essential components of the plumbing and heating pipe system of the type according to the invention also comprise a plastic-enclosed metallic joining sleeve for joining plastic pipes to fittings made of metallic materials, in which one sleeve end includes an offset bore for welding a plastic pipe therein while the other sleeve end includes an injected metallic connecting sleeve formed with a threaded portion for having a fitting screwed thereon, wherein at least one anti-twist means is provided on the outer surface of the connecting sleeve end, and parallel seal grooves extend around the outer cylindrical surface of the connecting sleeve.
As regards the tightness and working reliability of such sleeve connections, it is of decisive importance that the connection between the injected or moulded plastic material and the metallic sleeve surface should be such that the fluid to be conveyed through the sleeve will not pass along the outside of the metallic connecting sleeve, i.e. the formation of creep flows between the plastic material such as polypropylene and the metal should be inhibited because these might cause moisture to penetrate into the surrounding brickwork in cases in which the connecting sleeve is concealed.
It has been known for the purpose of preventing such creep fluid flows to provide a portion of the outer surface of the joining sleeve with flutes or grooves of square or rectangular cross-section into which the plastic material enters upon injection or moulding, but it has been found that due to the shrink stresses to which the plastic material is subjected cavities will be formed in the initially completely filled seal grooves through which cavities the moisture may creep.
It is therefore an object of the present invention to provide the seal grooves in such a way that irrespective of any possible shrink stresses a perfect seal is ensured between the plastic material and the surface of the connecting sleeve.
The specified object is solved in that the seal grooves have conical or V-shaped cross-section.
A further component of the plumbing and heating pipe system of the kind concerned in the invention is a reducer for connecting the plastic pipes to fittings of metallic materials, in which similar to the above-described joining sleeve one end has a bore for welding the plastic pipe while the other end has an injected metallic connecting sleeve formed with a screw thread for screw-connecting the fitting either internally or externally, and in which furthermore anti-twist means is provided relative to a plastic member surrounding the connecting sleeve, said anti-twist means being constituted by cavities in the form of slots, bores and the like formed in the end-side internal end of the connecting sleeve into which the injected plastic material will penetrate, wherein additionally annular grooves are formed on the cylindrical outer surface of the metallic connecting sleeve into which the injected plastic material will likewise peneterate.
Here, too, it has been found that anchoring of the plastic composition injection-moulded onto the surface of the connecting sleeve is not fully satisfactory within the annular grooves due to the shrink stresses occurring during solidification of the plastic material, so that in this case also leakages result from creep fluid flows which can be prevented in accordance with the present invention by the feature that the annular grooves of this reducer are likewise given a V-shaped cross-section.
Also, the plumbing and heating pipe system of the kind according to the invention comprises a shut-off valve made of plastic material and including a plastic-sheathed metallic valve seat for mounting in plumbing and heating pipe systems, comprising two series-arranged pipe connecting sleeve portions and an internally threaded valve body receptacle therebetween which constitutes the valve seat and into which the valve body may be screwed.
Such plastic valves or plastic-sheathed valves exhibit the significant drawback that their metallic valve seat is in the form of a T-piece which is a relatively complex geometrical shape requiring considerable effort in respect of manufacture and processing and serving the purpose of firmly anchoring the valve seat body within said plastic sheath material.
It is a further drawback that the fluid tightness of the valve seat body inside the plastic material is not fully satisfactory because in this case also creep paths for the fluid will be formed due to the shrink stresses occurring when the plastic material is cooled subsequent to being injected or moulded. It is therefore a further object of the invention--although this is closely related to the first-mentioned object--to design the shut-off valve of the specified kind in such a way that the manufacturing costs are reduced while the working reliability and especially the tightness of the reducer is improved.
In accordance with the invention the specified object is solved in that the metallic valve body receptacle is a rotary body of cylindrical configuration which is provided on a portion of its cylindrical outer surface with flow bores which extend transversely to its longitudinal axis and which can be closed by means of the valve body, while it is provided on other portions of its surface with anti-twist means as well as with sealing elements against fluid leakage from the pipe connecting sleeve members, so that the valve seat member need not be formed as a T-piece.
Another important component of the plumbing and heating pipe system of the present invention is a pressure-type screw connection which is particularly suitable for hot water and aggressive liquids and is used to interconnect two conduits or a conduit and a nipple such that this joint can withstand relatively high pressures and temperatures without loss of tightness.
This is achieved in accordance with the present invention by a union nut provided with an internal screw thread and having a bottom-side and a central opening for the passage of one of two pipes therethrough, the union nut being adapted to receive an end flange of the one pipe and to be screw-connected with the external screw thread of a nut surrounding the other liquid pipe, the bottom end of said further nut being adapted to be screwed against the end flange of the second liquid pipe, said end flange resting against the end flange of the first liquid pipe.
It is ensured by this configuration that even fluid pipes made of plastic material, especially polypropylene, which are resistant to most aggressive and hot liquids, may be screwed together in such a way that the screw connection will not become unscrewed under the action of pressure and heat.
Also, the plumbing and heating pipe system according to the invention comprises a reducer developed for the connection of radiators in rooms, especially for installation of the heating pipes so as to be concealed by the skirting board, said reducer comprising two interconnected pipe members which follow the extension of the skirting board and one of which is adapted for connection to the heating water flow while the other one is adapted for connection to the heating water return.
When already existing buildings, especially old buildings, are equipped with central heating as is frequently necessary when old buildings are refurbished, the concealed installation of the heating pipes is often avoided because of the costs and also for structural reasons so that the heating pipes are disposed behind the skirting board to be concealed thereby, the heating water flow and return pipes being installed on top of each other along the wall of the room. In these cases the radiators are connected to the thus installed heating pipes by means of reducers for connecting the hot-water flow and return of the radiators to the corresponding pipes.
Due to the superposed installation of the two heating pipes in the vicinity of the skirting board it was necessary until recently to pass the flow and the return of the respective radiator over the upper heating pipe so as to have it terminate into the lower heating pipe. Thereby the planar provision of the heating pipes along the wall was interrupted by bulges which require either a corresponding interruption of the skirting board with consequent adapting work and an awkward appearance, or the provision of corresponding recesses in the brickwork for accommodating such connections.
It is therefore an additional object of the present invention to design the reducer of the above-specified kind in such a way that the two pipe members for the heating water flow and return are interconnected in such a way that complete concealment by the skirting board is made possible without having to cut open or otherwise change the appearance of the board to this end.
In accordance with the present invention the specified object is solved in that the two pipe members are disposed one above the other and the upper pipe member includes the two pipe unions for the heating water flow and return, one of said pipe unions bridging the cross-section of the upper pipe member inside the contour of said pipe member by means of a bridging passageway which opens into the bottom pipe member inside the contour of the same.
Finally, the plumbing and heating pipe system according to the present invention also comprises an arrangement for a welding device for welding parallel plastic pipes by means of which an end-side equalization of the plastic pipe lengths can be made. When installing pipelines of such systems, such plastic pipes frequently require welding to pipe fittings such as reducing means, pipe sleeves, elbows and T-pieces, and in many cases such pipes must be installed in parallel to each other and accurately equalized in respect of their ends.
In order to achieve a rapid length equalization and to ensure that such equalization is thereafter maintained, i.e. that the parallel pipes cannot be moved relative to each other while work is performed thereon for instance with a welding device, an arrangement has been developed in accordance with the invention which is characterized by a straddling body adapted to be arranged on the parallel plastic pipes and having a bracket member adapted to be pivoted upwardly, said bracket member in its upwardly pivoted position being swingable downwardly transversely to the longitudinal pipe axes over the pipe ends and having an end plate against which the end faces of the pipe ends abut.